Keystore 2.0: Shim around the basic functionality of Keystore 2.0 (ebd964a0) · Commits · e / os / android_frameworks_base

api/current.txt

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		@@ -42742,6 +42742,12 @@ package android.security.identity {

		package android.security.keystore {

		public class BackendBusyException extends java.security.ProviderException {
		ctor public BackendBusyException();
		ctor public BackendBusyException(@NonNull String);
		ctor public BackendBusyException(@NonNull String, @NonNull Throwable);
		}

		public class KeyExpiredException extends java.security.InvalidKeyException {
		ctor public KeyExpiredException();
		ctor public KeyExpiredException(String);

core/api/current.txt

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		@@ -40910,6 +40910,12 @@ package android.security.identity {

		package android.security.keystore {

		public class BackendBusyException extends java.security.ProviderException {
		ctor public BackendBusyException();
		ctor public BackendBusyException(@NonNull String);
		ctor public BackendBusyException(@NonNull String, @NonNull Throwable);
		}

		public class KeyExpiredException extends java.security.InvalidKeyException {
		ctor public KeyExpiredException();
		ctor public KeyExpiredException(String);

keystore/java/android/security/CheckedRemoteRequest.java

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		/*
		* Copyright (C) 2020 The Android Open Source Project
		*
		* Licensed under the Apache License, Version 2.0 (the "License");
		* you may not use this file except in compliance with the License.
		* You may obtain a copy of the License at
		*
		* http://www.apache.org/licenses/LICENSE-2.0
		*
		* Unless required by applicable law or agreed to in writing, software
		* distributed under the License is distributed on an "AS IS" BASIS,
		* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
		* See the License for the specific language governing permissions and
		* limitations under the License.
		*/

		package android.security;

		import android.os.RemoteException;

		/**
		* This is a Producer of {@code R} that is expected to throw a {@link RemoteException}.
		*
		* It is used by Keystore2 service wrappers to handle and convert {@link RemoteException}
		* and {@link android.os.ServiceSpecificException} into {@link KeyStoreException}.
		*
		* @hide
		* @param <R>
		*/
		@FunctionalInterface
		interface CheckedRemoteRequest<R> {
		R execute() throws RemoteException;
		}

keystore/java/android/security/KeyStore2.java

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		/*
		* Copyright (C) 2020 The Android Open Source Project
		*
		* Licensed under the Apache License, Version 2.0 (the "License");
		* you may not use this file except in compliance with the License.
		* You may obtain a copy of the License at
		*
		* http://www.apache.org/licenses/LICENSE-2.0
		*
		* Unless required by applicable law or agreed to in writing, software
		* distributed under the License is distributed on an "AS IS" BASIS,
		* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
		* See the License for the specific language governing permissions and
		* limitations under the License.
		*/

		package android.security;

		import android.annotation.NonNull;
		import android.compat.annotation.ChangeId;
		import android.compat.annotation.EnabledAfter;
		import android.os.Build;
		import android.os.RemoteException;
		import android.os.ServiceManager;
		import android.os.ServiceSpecificException;
		import android.system.keystore2.IKeystoreService;
		import android.system.keystore2.KeyDescriptor;
		import android.system.keystore2.KeyEntryResponse;
		import android.system.keystore2.ResponseCode;
		import android.util.Log;

		import java.util.Calendar;

		/**
		* @hide This should not be made public in its present form because it
		* assumes that private and secret key bytes are available and would
		* preclude the use of hardware crypto.
		*/
		public class KeyStore2 {
		private static final String TAG = "KeyStore";

		private static final int RECOVERY_GRACE_PERIOD_MS = 50;

		/**
		* Keystore operation creation may fail
		*
		* Keystore used to work under the assumption that the creation of cryptographic operations
		* always succeeds. However, the KeyMint backend has only a limited number of operation slots.
		* In order to keep up the appearance of "infinite" operation slots, the Keystore daemon
		* would prune least recently used operations if there is no available operation slot.
		* As a result, good operations could be terminated prematurely.
		*
		* This opens AndroidKeystore up to denial-of-service and unintended livelock situations.
		* E.g.: if multiple apps wake up at the same time, e.g., due to power management optimizations,
		* and attempt to perform crypto operations, they start terminating each others operations
		* without making any progress.
		*
		* To break out of livelocks and to discourage DoS attempts we have changed the pruning
		* strategy such that it prefers clients that use few operation slots and only briefly.
		* As a result we can, almost, guarantee that single operations that don't linger inactive
		* for more than 5 seconds will conclude unhampered by the pruning strategy. "Almost",
		* because there are operations related to file system encryption that can prune even
		* these operations, but those are extremely rare.
		*
		* As a side effect of this new pruning strategy operation creation can now fail if the
		* client has a lower pruning power than all of the existing operations.
		*
		* Pruning strategy
		*
		* To find a suitable candidate we compute the malus for the caller and each existing
		* operation. The malus is the inverse of the pruning power (caller) or pruning
		* resistance (existing operation). For the caller to be able to prune an operation it must
		* find an operation with a malus higher than its own.
		*
		* For more detail on the pruning strategy consult the implementation at
		* https://android.googlesource.com/platform/system/security/+/refs/heads/master/keystore2/src/operation.rs
		*
		* For older SDK version, KeyStore2 will poll the Keystore daemon for a free operation
		* slot. So to applications, targeting earlier SDK versions, it will still look like cipher and
		* signature object initialization always succeeds, however, it may take longer to get an
		* operation.
		*
		* All SDK version benefit from fairer operation slot scheduling and a better chance to
		* successfully conclude an operation.
		*/
		@ChangeId
		@EnabledAfter(targetSdkVersion = Build.VERSION_CODES.R)
		static final long KEYSTORE_OPERATION_CREATION_MAY_FAIL = 169897160L;

		// Never use mBinder directly, use KeyStore2.getService() instead or better yet
		// handleRemoteExceptionWithRetry which retries connecting to Keystore once in case
		// of a remote exception.
		private IKeystoreService mBinder;


		@FunctionalInterface
		interface CheckedRemoteRequest<R> {
		R execute(IKeystoreService service) throws RemoteException;
		}

		private <R> R handleRemoteExceptionWithRetry(@NonNull CheckedRemoteRequest<R> request)
		throws KeyStoreException {
		IKeystoreService service = getService(false /* retryLookup */);
		boolean firstTry = true;
		while (true) {
		try {
		return request.execute(service);
		} catch (ServiceSpecificException e) {
		Log.e(TAG, "KeyStore exception", e);
		throw new KeyStoreException(e.errorCode, "");
		} catch (RemoteException e) {
		if (firstTry) {
		Log.w(TAG, "Looks like we may have lost connection to the Keystore "
		+ "daemon.");
		Log.w(TAG, "Retrying after giving Keystore "
		+ RECOVERY_GRACE_PERIOD_MS + "ms to recover.");
		interruptedPreservingSleep(RECOVERY_GRACE_PERIOD_MS);
		service = getService(true /* retry Lookup */);
		firstTry = false;
		} else {
		Log.e(TAG, "Cannot connect to Keystore daemon.", e);
		throw new KeyStoreException(ResponseCode.SYSTEM_ERROR, "");
		}
		}
		}
		}


		private KeyStore2() {
		mBinder = null;
		}

		public static KeyStore2 getInstance() {
		return new KeyStore2();
		}

		private synchronized IKeystoreService getService(boolean retryLookup) {
		if (mBinder == null \|\| retryLookup) {
		mBinder = IKeystoreService.Stub.asInterface(ServiceManager
		.getService("android.system.keystore2"));
		}
		return mBinder;
		}

		void delete(KeyDescriptor descriptor) throws KeyStoreException {
		handleRemoteExceptionWithRetry((service) -> {
		service.deleteKey(descriptor);
		return 0;
		});
		}

		/**
		* List all entries in the keystore for in the given namespace.
		*/
		public KeyDescriptor[] list(int domain, long namespace) throws KeyStoreException {
		return handleRemoteExceptionWithRetry((service) -> service.listEntries(domain, namespace));
		}

		/**
		* Create a grant that allows the grantee identified by {@code granteeUid} to use
		* the key specified by {@code descriptor} withint the restrictions given by
		* {@code accessVectore}.
		* @see IKeystoreService#grant(KeyDescriptor, int, int) for more details.
		* @param descriptor
		* @param granteeUid
		* @param accessVector
		* @return
		* @throws KeyStoreException
		* @hide
		*/
		public KeyDescriptor grant(KeyDescriptor descriptor, int granteeUid, int accessVector)
		throws KeyStoreException {
		return handleRemoteExceptionWithRetry(
		(service) -> service.grant(descriptor, granteeUid, accessVector)
		);
		}

		/**
		* Destroys a grant.
		* @see IKeystoreService#ungrant(KeyDescriptor, int) for more details.
		* @param descriptor
		* @param granteeUid
		* @throws KeyStoreException
		* @hide
		*/
		public void ungrant(KeyDescriptor descriptor, int granteeUid)
		throws KeyStoreException {
		handleRemoteExceptionWithRetry((service) -> {
		service.ungrant(descriptor, granteeUid);
		return 0;
		});
		}

		/**
		* Retrieves a key entry from the keystore backend.
		* @see IKeystoreService#getKeyEntry(KeyDescriptor) for more details.
		* @param descriptor
		* @return
		* @throws KeyStoreException
		* @hide
		*/
		public KeyEntryResponse getKeyEntry(@NonNull KeyDescriptor descriptor)
		throws KeyStoreException {
		return handleRemoteExceptionWithRetry((service) -> service.getKeyEntry(descriptor));
		}

		/**
		* Get the security level specific keystore interface from the keystore daemon.
		* @see IKeystoreService#getSecurityLevel(int) for more details.
		* @param securityLevel
		* @return
		* @throws KeyStoreException
		* @hide
		*/
		public KeyStoreSecurityLevel getSecurityLevel(int securityLevel)
		throws KeyStoreException {
		return handleRemoteExceptionWithRetry((service) ->
		new KeyStoreSecurityLevel(
		service.getSecurityLevel(securityLevel)
		)
		);
		}

		/**
		* Update the subcomponents of a key entry designated by the key descriptor.
		* @see IKeystoreService#updateSubcomponent(KeyDescriptor, byte[], byte[]) for more details.
		* @param key
		* @param publicCert
		* @param publicCertChain
		* @throws KeyStoreException
		* @hide
		*/
		public void updateSubcomponents(@NonNull KeyDescriptor key, byte[] publicCert,
		byte[] publicCertChain) throws KeyStoreException {
		handleRemoteExceptionWithRetry((service) -> {
		service.updateSubcomponent(key, publicCert, publicCertChain);
		return 0;
		});
		}

		/**
		* Delete the key designed by the key descriptor.
		* @see IKeystoreService#deleteKey(KeyDescriptor) for more details.
		* @param descriptor
		* @throws KeyStoreException
		* @hide
		*/
		public void deleteKey(@NonNull KeyDescriptor descriptor)
		throws KeyStoreException {
		handleRemoteExceptionWithRetry((service) -> {
		service.deleteKey(descriptor);
		return 0;
		});
		}

		protected static void interruptedPreservingSleep(long millis) {
		boolean wasInterrupted = false;
		Calendar calendar = Calendar.getInstance();
		long target = calendar.getTimeInMillis() + millis;
		while (true) {
		try {
		Thread.sleep(target - calendar.getTimeInMillis());
		break;
		} catch (InterruptedException e) {
		wasInterrupted = true;
		} catch (IllegalArgumentException e) {
		// This means that the argument to sleep was negative.
		// So we are done sleeping.
		break;
		}
		}
		if (wasInterrupted) {
		Thread.currentThread().interrupt();
		}
		}

		}

keystore/java/android/security/KeyStoreOperation.java

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+141 −0

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		/*
		* Copyright (C) 2020 The Android Open Source Project
		*
		* Licensed under the Apache License, Version 2.0 (the "License");
		* you may not use this file except in compliance with the License.
		* You may obtain a copy of the License at
		*
		* http://www.apache.org/licenses/LICENSE-2.0
		*
		* Unless required by applicable law or agreed to in writing, software
		* distributed under the License is distributed on an "AS IS" BASIS,
		* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
		* See the License for the specific language governing permissions and
		* limitations under the License.
		*/

		package android.security;

		import android.annotation.NonNull;
		import android.os.RemoteException;
		import android.os.ServiceSpecificException;
		import android.security.keymaster.KeymasterDefs;
		import android.system.keystore2.IKeystoreOperation;
		import android.system.keystore2.KeyParameter;
		import android.system.keystore2.ResponseCode;
		import android.util.Log;

		/**
		* @hide
		*/
		public class KeyStoreOperation {
		static final String TAG = "KeyStoreOperation";
		private final IKeystoreOperation mOperation;
		private final Long mChallenge;
		private final KeyParameter[] mParameters;

		public KeyStoreOperation(
		@NonNull IKeystoreOperation operation,
		Long challenge,
		KeyParameter[] parameters
		) {
		this.mOperation = operation;
		this.mChallenge = challenge;
		this.mParameters = parameters;
		}

		/**
		* Gets the challenge associated with this operation.
		* @return null if the operation does not required authorization. A 64bit operation
		* challenge otherwise.
		*/
		public Long getChallenge() {
		return mChallenge;
		}

		/**
		* Gets the parameters associated with this operation.
		* @return
		*/
		public KeyParameter[] getParameters() {
		return mParameters;
		}

		private <R> R handleExceptions(@NonNull CheckedRemoteRequest<R> request)
		throws KeyStoreException {
		try {
		return request.execute();
		} catch (ServiceSpecificException e) {
		switch(e.errorCode) {
		case ResponseCode.OPERATION_BUSY: {
		throw new IllegalThreadStateException(
		"Cannot update the same operation concurrently."
		);
		}
		default:
		// TODO Human readable string. Use something like KeyStore.getKeyStoreException
		throw new KeyStoreException(e.errorCode, "");
		}
		} catch (RemoteException e) {
		// Log exception and report invalid operation handle.
		// This should prompt the caller drop the reference to this operation and retry.
		Log.e(
		TAG,
		"Remote exception while advancing a KeyStoreOperation.",
		e
		);
		throw new KeyStoreException(KeymasterDefs.KM_ERROR_INVALID_OPERATION_HANDLE, "");
		}
		}

		/**
		* Updates the Keystore operation represented by this object with more associated data.
		* @see IKeystoreOperation#updateAad(byte[]) for more details.
		* @param input
		* @throws KeyStoreException
		*/
		public void updateAad(@NonNull byte[] input) throws KeyStoreException {
		handleExceptions(() -> {
		mOperation.updateAad(input);
		return 0;
		});
		}

		/**
		* Updates the Keystore operation represented by this object.
		* @see IKeystoreOperation#update(byte[]) for more details.
		* @param input
		* @return
		* @throws KeyStoreException
		* @hide
		*/
		public byte[] update(@NonNull byte[] input) throws KeyStoreException {
		return handleExceptions(() -> mOperation.update(input));
		}

		/**
		* Finalizes the Keystore operation represented by this object.
		* @see IKeystoreOperation#finish(byte[], byte[]) for more details.
		* @param input
		* @param signature
		* @return
		* @throws KeyStoreException
		* @hide
		*/
		public byte[] finish(byte[] input, byte[] signature) throws KeyStoreException {
		return handleExceptions(() -> mOperation.finish(input, signature));
		}

		/**
		* Aborts the Keystore operation represented by this object.
		* @see IKeystoreOperation#abort() for more details.
		* @throws KeyStoreException
		* @hide
		*/
		public void abort() throws KeyStoreException {
		handleExceptions(() -> {
		mOperation.abort();
		return 0;
		});
		}
		}